Machine and method for closing metal tubes



C. L. DEWEY MACHINE AND METHOD FOR CLOSING METAL TUBES 3 Sheets-Sheet 1Sept. 25, 1951 Filed March 11, 1943 Sept. 25, 1951 c. L. DEWEY 2,568,991

MACHINE AND METHOD FOR CLOSING METAL TUBES Filed March 11, 1943 3.Sheets-Sheet 2 P 25, 1951 c. L. DEWEY 2,568,991

MACHINE AND' METHOD FOR CLOSING METAL TUBES Filed March 11, 1943 sSheets-Sheet 5 12 flaw/76y,

Patented Sept. 25, 1951 MACHINE AND METHOD FOR CLOSING METAL TUBESClarence L. Dewey, Elkhart, Ind., assignor to Bendix AviationCorporation, South Bend, Ind., a corporation of Delaware ApplicationMarch 11, 1943, Serial No. 478,843

3 Claims.

The machine and method of the present invention are designed for thepurpose of inturning and closing the ends of metal tube sections by acold working process which will uniformly, accurately, and rapidlyreduce, configure, and close the end of the tube section and meanwhileregulate the wall thickness thereof so that thereafter the tube sectionmay be employed for the intended purpose.

In general, the method and mechanism, in the form hereafter described,involves the employment of a plurality of end-reducing rolls of specialdesign which as shown are mounted and driven in such a way with relationto each other as to positively revolve and rotate around the end of atube section which is held against rotation, but is fed inwardly inproper speed ratio to'the operation of the rolls, so that by a propercoordination of the feeding and reducing movements, the end of the tubewill be reduced and ultimately closed and configured in the intendedmanner.

The formation of the acting faces of the rolls constitutes an essentialfeature of the present invention, and in order to subserve the intendedpurpose, the acting faces of the rolls are of tapered or concaveconfiguration and provided with a multiplicity of longitudinallyextending ribs or corrugations which preferably extend in divergentrelation to the respective radial planes of the rolls, so that as therolls are rotated and revolved around the end of the tube, acircumferential series of tangential impacts and pressure contacts willbe maintained. By thus providing obliquely or spirally extending ribswith intervening grooves or valleys, the points of attack and impactupon the metal surface will be interspersed by intervening gaps whichallow areas of clearance for the redistribution of the metal fibers andavoid the excessive compression of all portions of the metal surfacewhich would result from the employment of smooth-surfaced rolls for alike purpose.

In order to fully disclose the nature of the present method andmechanism, reference is made to the accompanying drawings wherein-Figure 1 is a side elevation, partially broken away, of a machineembodying the principles of the present invention;

Fig. 2 is an end elevation looking toward the right-hand end of themachine in Fig. 1;

Fig. 3 is a cross-sectional View taken on line 3-3 of Fig. 1, showingthe clamp for fixedly holding the tube section;

Fig. 4 is a cross-sectional view taken on line 4-4 of Fig. 1;

Fig. 5 is a longitudinal sectional view taken through the center of themachine;

Figs. 6, '7, 8, 9, 10, 11, and 12 are a seriesof views showing the endsof tube sections of varying configuration and illustrative of likechanges which may be made in the configuration of the rolls; and

Fig. 13 is a diagrammatic view on a substantially enlarged scale,showing in full lines the tangential impacting action between successiveridges or ribs of the rotary tools or rolls and the peripheral surfaceof the tubular work, at the beginning of a reducing operation; andshowing in dotted lines, the said ridges or ribs, which subsequentlyengage the peripheral surface of the work in circumferentia lly spacedand successively lengthened tangentially directed impacts as the tubularwork is reduced.

In the present embodiment of the invention, the working portions of themachine are mounted upon a base 20 which may be extended to the degreedesired to, accommodate the extended lengths of tubing. Upon the base isslidably mounted a clamp-carriage block 2| which may be advanced by aplunger 22 suitably operated by hydraulic or similar means not shown.The clamp-carriage block in its upper surface is provided with a groove23 which coacts with a grooved face 24 of a clamping jaw 25 having aplunger 26 which may be operated hydraulically or otherwise to rigidlyclamp the tube section.

The tube section near its inner end is entered through a centering ring21 carried by a fixed standard 28 having a head 29 which surrounds thering, which latter is fixedly held in position by a set screw 30. Thecentering ring and clamp in conjunction with one another serve to holdthe inner end of the tube in position to present its axis in coincidentrelation to the axis of revolution of a pair of oppositely positionedrolls 7 3| whose peripheries stand in extremely close relation to saidaxis, so that as the rolls are revolved around the end of the tube andconcurrently rotated, the adjacent peripheries of the rolls will inunison present a substantially continuous working contact with themarginal wall around the end of the tube.

Each of the rolls is keyed upon the reduced forward end 32 of a spindle33 which has keyed thereon a spur pinion 34, the teeth of which meshwith the teeth of the internal gear ring 35. Each of the spindlesv ismounted within spaced ballbearing assemblies 36 and 31 separated by aspacer ring 38 housed within a cavity in a head 39 having inturnedflanges 40 which bear against the ball-bearing assemblies 36, whichflanges are sealed by packing rings 4| secured in place by caps 42. Therear end of the head 39 is closed by a disc 43 carried by a drivingspindle A l, which disc is secured to the head 39 by bolts 45, so thatthe rotation of the driving spindle will impart rotation to the head 39and cause the roll spindles and rolls to revolve around the axis of thedriving spindle as a center.

The driving spindle is mounted within spaced ball-bearing assemblies 48and 41 separated by a spacer ring 48 mounted Within a frame block '49.closed at its rear end by a cap plate 59 held in place by bolts The rearbearing assembly 4 is held in position by contact of the cap plate 5. inconjunction with a flanged collar 52, held in place by a nut 53 threadedonto the driving spindle, and the parts are sealed by a packing ring '54held in place by a flanged cap 55, thus permitting the bearings to beadequately lubricated.

The reduced outer end 56 of the driving spindle has mounted thereon agrooved pulley 51 which imparts rotation to the spindle.

The formation of the acting faces of the ribs or ridges'of the rolls isbest illustrated in Figs. 1, 4 and 13, and this formation and operationof the ribs constitutes one of the more important features of thepresent invention.

For purposes of illustration, concavely faced rolls are shown in thesefigures, which in conjunction are designed to impart to the end of thetube the hemispherical closure shown in Fig. 5, but it will beunderstood that the configuration of the acting surfaces of the rollsmay be of other formations, complimentary 'to the shapes illust-rated-inFigs. 6-12 inclusive and that such variations, or others of a like orsimilar character, are regarded as within the range 'of the presentinvention.

The rolls shown-in Figs. 1 and 4 are of enlarged diameter at their innerends and progressively reduced therefrom toward their outer ends whichfirst make contact with the incoming tube section. The roll face isprovided with a multiplicity of spaced ribs or ridges 58 and interveningvalleys 59 which alternate with one another in'uniform sequencethroughout the face of the roll. The ribs while extending in a generallylongitudinal direction trail backwardly and flare outwardly in obliquedivergent relation to' respective radial planes through the tips of theribs and are preferably of arcuate formation extending spirally as shownalthough they may for somepurposes be planate, and it will be understoodthat the term oblique" as here employed is intendedto cover anyequivalent departure, whether arcuate or planate, from a truly radialarrangement.

The flaring out of the ridges toward the rear may be by an unbrokenuniform curvature as shown in Fig. 5, or by variations in curvature asin Fig. 8, or by curvatures which in conjunction give the pointed-archformation of Fig. '7, or the flattened center formation shown in Figs. 6and 11. Fig. illustrates a truly conical formation in which the ribsurfaces present themselves in straight line contact to the tubesurfaces, and it will be understood that numerous combinations orvariations of such formations may be employed without departure from thespirit of the present invention.

It will be noted from an inspection of Fig. 4, and the enlargeddiagrammatic showing in Fig.

13 with due regard to the arrows indicating the direction of revolutionand rotation that the ridges of the rolls currently occupying the upperand lower positions as shown both extend obliquely or in divergentrelation to the radial plane which includes the points of tubecompression although the rolls occupy opposed positions to the tubesurface, and both rotate in clockwise direction as they revolve withinthe gear ring 35 in a counter-clockwise direction about the centrallydisposed tubular work.

With particular reference to the diagrammatic illustration in Fig. 13,it will be seen that by the provision of the obliquely disposed,circumferentially spaced rounded ridges, the tips of the ridges will insuccession, first forcibly engage and tangentially impact the tube wallat a plurality of progressively advanced and symmetrically disposedpoints therearound, at the free end of the tube, at the beginning of areducing operation. Thereafter, as the diameter of the tube end isreduced, further points on the obliquely disposed ridges willsuccessively tangentially impact the tube wall at circumferentialpoints, i. e. the progressively advanced points of impact with the tubewall are closely spaced therearound, and as the tube is reduced indiameter a greater length of each ridge will come into operativeengagement with the tube wall and travel spirally of the tube outwardlyfrom the point of maximum diameter of the tube to the reduced endthereon.

As indicated in Fig. 13, one of the ridges 58 is shown in point contactwith the tube wall at the beginning of a reducing operation, and theridge is shown in dotted lines as observed from the transverse plane ofthe tube at said-point of contact and toward theend of the tube whensame is fully reduced and-closed.

The concentric broken lines a, b, c, 11 indicate diagrammaticallysuccessive planes lengthwise of the tube in the progress of reductionthereof. Since the ridges have the same curvature as the finished end ofthe tube (Fig. 5), the central ridge in Fig. 13 will successivelycontact the tube end as a tangential impact further and further from theinitial point of contact indicated in full lines, for instance to thepoint a on the ridge when the tube end 'has been reduced to the plane ofthe circle a, and when the tube has been reduced to the plane of thecircles bcde the successiveridges will contact the wall thereofcontinuously from the point of initial operation to the respectivepoints b, 0, etc.

Since the rolls revolve around the tube, the right hand ridge indicatedin Fig. 13 will contact the tube to the left of the previous contact ofthe central ridge, or substantially at the point of tangency of arrow fwith the tube wall, and successive ridges will contact the tube at thepoints ofntangency of arrows g, h, and so on around the circumference ofthe tube at slightly spaced points, as explained above.

As seen in Fig. 4, each roll 31 will rotate through 720 for eachcomplete rotation of the head 39 through which rotation the rolls willbe carried around the tube, and since each roll has, as shown, 16ridges, the tube wall will. receive 64 tangential impacts in anytransverse plane of the end being reduced, and due to'the revolution ofthe rolls around the tube together with the continuously reduceddiameter of the tube toward the final closed end thereof, successiveimpacts by the respective ridges will be at differently spaced pointscircumferentiallyof the tube, with the result that no lines of impactwill appear on the wall of the finished closed end of the tube. In shortthese line points of impact and contact will progress obliquely. orspirally with respect to the tube surface, so that at no instance willthe ribs present an extended lateral contact with the tube, the ribsbeing rounded on their tips so that but a slight departure from a trulypoint contact at any time is presented. Such slight departure is due tothe current advancement of the tube as the crest of anengaging ribtangentially impacts and'moves across the surface and efi'ects at eachinstant a reduction in diameter by the minute area of contact currentlyafforded.

This reducing action due to the revolution of the rolls will be speededby the rotationof the 7 rolls themselves so that the direction ofrearward travel of the compressive impact points and contact linesagainst the tube surfacewil] be the resultant of a number of factorsincluding the speed of revolution of the rolls, the speed of rotation ofthe rolls, the obliquity or spirality of the ribbing, and the feedingspeed of the tube itself. Since it is possible to vary all of thesefactors with relation to one another, it is evident that the flow of themetal may be regulated to best meet any set of conditions encountered.

The reduction thus proceeds by the displacement of minute quantities ofmetal which are thus permitted to redistribute themselves freely andwithout excessive confinement so that galling or abrasion of the metalsurface is avoided and the reduction proceeds by minute stages which,however, by reason of the speed at which the rolls may be revolved willbe sufliciently accelerated to permit the operation to proceed rapidly,accurately, and with precision, so that uniformity of the resultingproduction is ensured by a proper timing of the operations.

By giving to the ridges the proper obliquity with relation to thedirection of rotation of the rolls, each ridge attack and impact will befirst centered against the forward peripheral wall of the open end ofthe tube so that the progressive impingements of the ridges around thetube will be generally and inwardly therefrom with the result that atall times the metal will be crowded metal in the same direction andcounter to the s.-

rotation of the rolls.

As the tube is advanced, its ends will be worked in or crowded towardthe center and progressively thickened until complete contact isestablished with the inner base ends of the ridges which oppose eachother from opposite sides of such close adjacency as to effect completeclosure of the tube and thereafter, if desired, the tube may be furtherfed inwardly which will additionally thicken the closed tip of the tubeto any desired degree.

In cases where it is not desired to completely close the end of thetube, the feeding may be terminated before complete closure results, orthe rolls may be spaced apart sufliciently to provide a gap or clearancethrough which the tip end of the tube will be projected in the form of areduced nose or extension of the character shown in Fig. 12 which may becompletely or partially closed.

Although for purposes of illustration I have illustrated the employmentof two oppositely disposed rolls whose axes occupy the. same plane ofcompression which intersects the axis of the tube, it is evident thatwhere close adjacency of the rolls. and complete closing of the tube isnot re,- quired, a group of three or more rolls might be employed, inwhich case angularly related planes of compression around the tube axiswould be presented so that where reference is made to the plane ofcompression, it will be understood that this term does not necessarilysignify asingle plane which includes the axes of all of the rollscomprising the group.

It will also be understood that the term point contact as applied totheattack and/or impact of the ridges against the terminal surface ofthe tube wall is not intended to be limited to a mathematical point butis intended to refer to a limited surface approximating a point asdistinguished from a broad-side engagement of the entire crest of theridge against the surface'of the tube.

It will also be understood that the term shoulders as applied to thesurface of the tube has reference to the slight elevations against whichthe attack of succeeding ribs are directed, which shoulders areconstantly recedingunder the successive attacks of oncoming ribs. Thecumulative effect of repeated recessions is to reduce the tube by stagesand until final closure is effected.

The process of the present invention is one which is adapted for thereduction and endclosing of tubes of varying metallic character andwithin a wide range of gauges and diameters, and although it is welladapted for the cold rolling of steel or other tubing of moderatediameter and gauge, it may be desirable in certain instances to heat thetube section in advance of the reducing operation, especially where atight welded closure is desired.

Furthermore, the desirability of preliminarily heating the tubes willdepend upon the use intended and the nature of the configuration andwall thickness to be imparted to the resulting product so thatvariations in this regard are deemed to be within the knowledge ofmechanics skilled in the art and having in mind the most desirablespeeds of revolution and rotation of the rolls in relation to theadvance of the tubing.

The configuration of the acting surfaces of the rolls is one which isintended to reduce any abrasive action and resultant heat from frictionto a minimum, so that in cold reducing operations only a moderate amountof heat will be developed, though ordinarily it may be desirable toemploy proper lubricants or cooling agents of the character commonlyemployed in operations of this general character.

Although it will be desirable in most instances to revolve and rotatethe rolls around a non-rotating tube and to advance the tube relativelyto the rolls, a reversal of one or both of these relationships betweenthe tube and rolls is contemplated so that in the claims, unlessotherwise indicated, it will be understood that relative rather thanabsolute movement of the parts is intended.

I claim:

1. The method of inturning the ends of metal tubing which comprisessimultaneously subjecting the exterior wall of the end of a tube to beinturned at a plurality of progressively advanced symmetrically disposedpoints to tangentially applied impacts, the impacts progressivelylengthening. axially of thetube'as the diameter or the tube is reduced.7

2. The method ofi inturning-theendsof metal tubing which consists :in.simultaneously subject ingthe exterior wall of theend 01 a tube to beinturned at a plunality oi -progressively. advanced circumferentiallyspaced points to tangentially applied impacts, theimpactsprogressively-lengthening axially of the tube as the diameterthereof is reduced, and the lengthening impactsextend-- ing obliquely tothe axis oi the tube-from: said points.

3. In a machine for inturning the ends of metal tubing, a plurality ofelongated reducing-rolls of generally circula-r cross section havingworking facw contoured to impart: the desired inturned shape to a tubeend and arranged to define a gradually converging-opening or roll:passto receive the end of the tube, saidfaces each beingprovided with aseries of 'circumferentiallyspaced blunt ridges each extending somewhatlongitudinallyof the tube and at an oblique ang'le to the adjacent axialplane of the tube through the contacting'ridge andfunctioning toexertsequentially engaging, spaced, progressively advancing reducingpoint impacts on the tube wall without chatter and resultant mutilationwhen rotated each on itsown axis, a rotatably mounted REFERENCES CITEDThe following references are. of record in the file of.this patent?UNITED STATESPATENTS Number Name Date 172,443 Ide Jan. 18, 18761,280,823" 'Oster Oct. 18, 1918 1,368,413 Stiefel; Feb. 15, 19212,234,182" Lauer Mar. 11, 1941 2,325,522 Lauer'et al July 2'7, 1943FOREIGN PATENTS Number Country- Date 19,420 Great Britain of 1909486,543 France Jan; 21, 1918 539,991 France Apr. 10, 1922

